We propose to carry on studies in the following areas; 1. Theoretical studies of spatial and density resolution and radiation dose as well as the possible extension of CT scanning to three dimensional imaging. 2. Studies on our bench top fan beam x-ray system, including analysis of the high pressure xenon chamber, electronics, digital to analog converters and computer algorithms. We propose an extensive program of study of phantoms to define the performance characteristics of the system. 3. Study of energy sensitive detection and Z scanning. We intend to study various techniques to obtain this information. Among these are the use of split-finger detectors, the use of a rotating variable filter, and the use of multiple KVP x-rays. From this information we propose to obtain simultaneous electron density and Z images. 4. Using the bench top system we propose to study application of CT scanning to gated imaging of the heart. 5. Using the bench top system we propose to investigate applications of CT to various problems of cancer diagnosis and therapy. 6. Using the bench top system, we intend to investigate the possibility of imaging small animals for medical research.